Pre Amp Voltage

[Mike75 10+ year member]

SO....Yes or NO....4 volts $400 2 volts $200

 

[lrgaslife 10+ year member]

If it was me. I wouldn't even consider anything less than 4v.

 

[iceteebone 5,000+ posts]

2 volts will be fine. how come people don't look for low impedence or non clipping preouts //content.invisioncic.com/y282845/emoticons/crap.gif.7f4dd41e3e9b23fbd170a1ee6f65cecc.gif oh well more is better i guess.

 

[helotaxi 5,000+ posts]

As long as the preamp voltage matches the input range of your amp and isn't clipping, it shouldn't matter. With crappy RCAs or cheap amps, it might make a difference, but if you care enough to bother with a high-end head unit and then chances are you aren't goingto cut corners on the amps or RCAs either. Like DBFan said, you will never see much in the way of voltage on the lines while listening to music anyway. Turn the volume down 3dB and that is a reduction of close to 50% of the voltage.

 

[bobibo 10+ year member]

SO....Yes or NO....4 volts $400 2 volts $200

you could get a 5v for 300$ mannnn on ebay(Kenwood MP828, very good head unit 5v with 4-band EQ with SRS WOW and many options for cheap price), i suggest you get the highest volt possible IMO, get the most you can... what head unit are you thinkin for 400$?

 

[squeak9798 5,000+ posts]

As long as your amplifier isn't noisy with a higher gain setting, there is no audible difference between 2V, 4V or 8V. And most quality amplifiers these days will not have much audible noise with a higher gain setting. Higher preout voltages do not inherently sound better, and are not "louder" with a properly adjusted gain.

If the preout voltage is the only difference between those two decks, save your money and go with the lower voltage unit. But for a $200 price difference, I'd guess that there are differences in terms of features/etc, in which case I would recommend you go with the more expensive unit if those features are of use to you. But notice that the reason to go with the higher priced unit is for the possibility of more features, and not the preamp voltage.

 

[helotaxi 5,000+ posts]

I would focus more on features that you need/want rather than just preout voltage. As was mentioned above, unclipped outputs are much more important than raw *peak* voltages. Most every HU I've seen bench tested failed to make its rated output voltage with a reasonable level of distortion or without clipping, and most required max bass boost for them to even approach their rated voltage. It's not something worth getting hung up about because with decent quality components it just doesn't matter.

 

[Nightfall 10+ year member]

...and are not "louder" with a properly adjusted gain.

But wouldn't an amp recieving 4v vs. 2v not have to have the gain turned up *as* high to be properly adjusted? Wouldn't it be less stress on the electrical system then? Wouldn't it be easier on the amp? I'm not trying to sound cocky if that is how it comes off, merely trying to learn. //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif

 

[Mike75 10+ year member]

I am trying to decide between the Alpine 9855, and the Kenwood 25th anniversary deck....But Kenwood makes many decks that are much less money, and they are 4 volt....I know I will get trashed for this, but I the amp I will be running is the Audiobahn A4801T....Before you trash it, look it up on a few sites and look at the info....Please help me decide what to do. Thank you.

 

[squeak9798 5,000+ posts]

But wouldn't an amp recieving 4v vs. 2v not have to have the gain turned up *as* high to be properly adjusted?

Yes, but the only possible thing you will gain there is a better SNR (signal to noise ratio). If you had no audible noise with a 2V signal, going to 4V will not gain you anything.

Wouldn't it be less stress on the electrical system then?

No. 1kw is 1kw, no way around it.

Wouldn't it be easier on the amp?

Not really. The amplifier is still producing 1kw. The same amount of power is still flowing through the amplifier. Most amplifiers were designed to safely produce rated power output with as little as .2V

I know this is a total oversimplification....but essentially what you are doing with the gain is decreasing the level of the input signal so that the amplifier will produce rated output power, but yet not clip while attempting to do so. With a higher preamp input voltage, you need to decrease it more. That's all.

 

[squeak9798 5,000+ posts]

I am trying to decide between the Alpine 9855, and the Kenwood 25th anniversary deck....But Kenwood makes many decks that are much less money, and they are 4 volt....I know I will get trashed for this, but I the amp I will be running is the Audiobahn A4801T....Before you trash it, look it up on a few sites and look at the info....Please help me decide what to do. Thank you.

I don't know much about the Kenwood....but what features do you need in a HU? Which one of those decks has the features you need?

 

[thch 10+ year member]

But wouldn't an amp recieving 4v vs. 2v not have to have the gain turned up *as* high to be properly adjusted? Wouldn't it be less stress on the electrical system then? Wouldn't it be easier on the amp? I'm not trying to sound cocky if that is how it comes off, merely trying to learn. //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif

common misconception. the input siganl from the RCA's is a control signal -- it provides insignifigant energy for the amp to actually do anything. with transistors it is easy to get a voltage gain of over 10,000. in fact that's how amps end up working. you build an amp with two inputs and a high gain. then hook it up so it "amplifies the difference of the inputs by a high gain". then you take the output from the amp and hook it up to the input. basically the output would never be more then 1/gain away from the input voltage.

further, the power dissipated by the amp is dominated by the voltage across the output transistors and the current through them. if you have a power supply voltage of 30V, and an output voltage of 20V, then you have 10V across the transistor. if you have 5A of output current (for a 4ohm load) you will have 10V * 5A = 50W of power loss at this moment. this power loss spec is based only upon the output signal, and not the input signal -- so long as the output signal is the same, it will not matter what input caused it.

 

[Mike75 10+ year member]

Wow, it sounds like you guys really understand this...I am trying to learn, slowly but surely....To answer your questions, In all honesty, I really only need the HU to play cd's, the radio, and have great SQ...Therefore I feel that I need good tuning capabilities, so probably a parametric EQ, although I am a bit unsure of how to use one of those to its best potential...Also, for SQ, I felt that I needed at least 4 volts....I listened to several systems in friend's cars, and the one that was superior had a 5 volt HU....Maybe just coincidence, I don't know....So if you guys could point me in the right direction in simple terms, I would really appreciate it. Thank you

 

[DBfan187 5,000+ posts]

psychoacoustics pwnt you good!

You more than likely heard a difference in more power/install/processing/higher gains or a combination of each.

 

[squeak9798 5,000+ posts]

I listened to several systems in friend's cars, and the one that was superior had a 5 volt HU....Maybe just coincidence,

Yes, it was likely just coincidence.

Your "listening experience" serves as anything but a valid comparison of preout voltages. There were literally thousands of variables...everything from your seating position in the vehicle, to the installation and setup of the systems, the equipment used in the systems, to the vehicle itself. Out of those thousands of variables, it's impossible to conclude that something as insignificant as preout voltage had a contributing hand in the differences you heard.

Especially since we can straight up tell you.....it's not one of the reasons //content.invisioncic.com/y282845/emoticons/biggrin.gif.d71a5d36fcbab170f2364c9f2e3946cb.gif

So if you guys could point me in the right direction in simple terms, I would really appreciate it. Thank you

I would personally go for that Alpine you mentioned, out of those two decks.